Apparatus for preventing excessive tension in electrical conductors reeved in uprights



Jan. 27, 1970 A. E- Pl 3,491,905 APPARATUS FOR PREVENTING EXCESSIVE TENSION IN ELECTRICAL CONDUCTORS REEVED IN UPRIGHTS Filed June 12. 1967 4 Sheets-Sheet 1 FIG. I

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BY v, .l

ATTORNEY Jan. 27, 1970 3,491,905

A. E. Pl APPARATUS FOR PREVENTING EXCESSIVE TENSION IN ELECTRICAL CONDUCTOBS REEVED IN UPRIGH TS Filed June 12, 196'? 4 Sheets-Sheet 2 I FIG. '2 36 I48 INVENTOR ALBERTO E. Pl

ATTOR N EY Jan. 27, 1970 A. E. Pl 3,491,905

APPARATUS FOR PREVENTING'EXCESSIVE TENSION IN ELECTRICAL CONDUCTORS REEVED IN UPRIGHTS F il'd June 12, 19677 4 Sheets-Sheet 3 FIG. 3

INVENTOR ALBERTO E. PI

ATTORNEY Jan. 27, 1970 A. E4

APPARATUS FOR PREVENTING EXCESSIVE TENSION IN v ELECTRICAL CONDUCTORS REEVED IN UPRIGHTS Filed June 12. 1967 4 Sheets-Sheet 4 FIG. 5

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ATTORNEY nited States Patent 3,491,905 APPARATUS FOR PREVENTING EXCESSIVE TEN- SION IN ELECTRICAL CONDUCTORS REEVED IN UPRIGHTS Alberto E. Pi, Battle Creek, Mich., assrgnor: to Clark Equipment Company, a corporation of Michigan Filed June 12, 1967, Ser. No. 645,368 Int. Cl. B66f 9/06, 9/18 US. Cl. 214-620 10 Claims ABSTRACT OF THE DISCLOSURE Apparatus for preventing excessive tension being exerted on electrical conductors reeved between the mast and an attachment mounted on the carriage of two or three-stage extendible uprights.

Background of the invention The field of art to which the invention pertains includes elevators, and more specifically portable elevators.

Some attachments mounted on extendible uprights 1nclude, for example, three fluid-operated motors. One arrangement for operating these fluid motors utillzesa pair of fluid conduits reeved between the mast and carriage, a three-position valve, a pair of solenoids for shifting the valve and a pair of electric conductors for energizing the solenoids. It is desirable from the standpoint of compactness, simplicity and minimization of the number of parts required to have the electrical conductors follow generally the fluid conduits. However, the fluid conduits are elastic, and so shorten by approximately four per cent when carrying pressurized fluid. This presents a problem in regard to the electrical conductors because they are substantially non-stretchable. Thus, an object of mynnvention is to provide apparatus to accommodate electrical conductors reeved with elastic fluid conduits to changes in length of the fluid conduits.

Summary of the invention In carrying out my invention in a preferred embodiment thereof, 1 provide a sheave, a pair of electrical conductors fixed at one of their ends and trained around the sheave in opposite directions and a pair of springs, each sprlng being connected to a different one of the electrical conductors for maintaining tension on the respective conductor.

The above and other objects, features and advantages of my invention will be more readily understood by persons skilled in the art when the detailed description is taken in conjunction with the drawing.

Brief description of the drawing FIGURE 1 is a rear-quarter perspective view of a portion of a lift truck with the upright extended and showing to advantage my invention,

FIGURE 2 is an elevational view from the rear of a three-stage upright in the fully collapsed position and embodying my invention,

FIGURE 3 is a fragmentary plan view on an enlarged scale of the upright,

FIGURE 4 shows in enlarged detail the apparatus and arrangement for reeving the fluid conduits and electrical conductors between the mast and intermediate slide of the upright, and

FIGURE 5 is similar to FIG. 4, except that the lower run of fluid conduit has been supplied with pressurized fluid.

Description of the preferred embodiment Referring to FIG. 1, the reference numeral 10 denotes generally a portion of a lift truck which includes a seat 12, a cowl 14, a plurality of control levers 16 mounted on the cowl and a steering control wheel 18 also mounted on the cowl.

Referring now also to FIGS. 2 and 3, an extendible upright 20 is mounted on lift truck 10 forwardly thereof. Upright 20 includes a mast 22, an intermediate slide 24 telescoped in mast 22 and movable longitudinally thereof, an inner slide 26 telescoped in intermediate slide 24 and movable longitudinally thereof, a carriage 28 mounted on inner slide 26 and movable longitudinally thereof, and a multiple ram fluid motor 30 which includes an outer cylinder 32 connected to intermediate slide 24. Mast 22 includes a pair of C-shaped channels 34 connected by a plurality of cross braces 36 to form a rigid unitary structure. Intermediate slide 24 includes a pair of I-beams or rails 38 connected by a plurality of cross braces 40 to form a rigid unitary structure, and similarly inner slide 26 includes a pair of I-beams or rails 42 connected by a plurality of cross braces 44 to form a rigid unitary struo ture. Also, a pair of chains 46 are connected at one of their ends to carriage 28 and at the other of their ends to an anchor plate 48 on outer cylinder 32 of fluid motor 30 and reeved over a pair of sprockets 50 which are mounted for rotation on a cross arm 52 that is connected to motor 30.

When upright 20 is in the fully collapsed position with carriage 28 in the lowermost position (FIG. 2) and pressurized fluid is supplied to motor 30, the motor extends to cause cross arm 52 to move upwardly until inner slide 26 is engaged by the cross arm. At this point carriage 28 has been raised about 18 inches in the particular upright shown. Further extension of motor 30 then causes inner slide 26 to move upwardly also while carriage 28 continues to move upwardly along the inner slide. When carriage 28 has reached the top of inner slide 26 the inner slide is fully extended. If additional pressurized fluid is supplied to motor 30 from the condition in which the inner slide 26 has been fully extended out of intermediate slide 24, fluid motor 30 is extended at the bottom thereof so that intermediate slide 24 is pulled vertically outwardly of mast 22 by inner slide 26 to its full extension.

While no attachment has been shown mounted on carriage 28, it will be understood that there are available a great many types of attachments which can be mounted on the carriage. Some of these attachments, such as a rotating roll clamp mounted on a side shifter require three fluid motors for operation. Lift truck 10 is provided with a pump which draws fluid from a reservoir and pressurizes the fluid. Obviously, means must be provided for supplying the pressurized fluid to the fluid motors of the attachment and then returning the fluid to the reservoir.

Mounted on carriage 28 is a valve 54 which, although it is shown mounted on carriage 28, could just as well be mounted on an attachment carried by the carriage. Valve 54 includes a spool which is actuatable from a first position to a second or third position by means of a pair of solenoids 56 and 58. Valve 40 also includes a pair of ports 60 and 62 and three pairs of motor ports. Thus, by shifting the valve spool between the three positions thereof ports 60 and 62 can be connected to the three different pairs of motor ports so that the three separate fluid motors of the attachment can be operated independently of each other from a single pair of fluid supply and return conduits. Of course, if an attachment is being used which embodies only two separate fluid motors, then a valve having a spool shiftable to only two positions is all that is required, and so only a single solenoid would be necessary in conjunction with such a valve.

A rigid fluid conduit 64 is connected to port 60 at one end and is connected at the other end to a junction block 66 on carriage 28 which is mounted as shown in FIG. 3. Similarly, a rigid conduit 68 is connected to port 62 andto a junction block 70.

Connected at one end thereof to junction block 66 and hence conduit 64 is a flexible fluid conduit 72 which is reeved over a dual sheave assembly 74 that is mounted on cross arm 52 outwardly of the adjacent sprocket 50 and connected to another junction block 76 which is mounted on anchor plate 58. Another flexible fluid conduit 78 is connected at one end to junction block 76 and hence conduit 72 and connected at the other end thereof to a fitting 80 mounted on a bracket 82 which is connected to one of the rails 38 of intermediate slide 24.

Likewise, a flexible fluid conduit 84 is connected at one end thereof to junction block 70 and hence conduit 68, reeved over a dual sheave assembly 85 mounted for rotation on cross arm 52 outwardly of adjacent sprocket 50 and connected to a junction block 86 which is mounted on anchor plate 48. Another flexible fluid conduit 88 is connected at one end thereof to junction block 86 and hence conduit 84 and connected at the other end thereof to a fitting 90 mounted on bracket 82.

The reeving of conduits 72, 78, 84 and 88 which has been described thus far accommodates the relative movement between carriage 28 and inner slide 26 and the relative movement between inner slide 26 and intermediate slide 24.

In order to accommodate the relative movement between intermediate slide 24 and mast 22 a conduit reevin g which is different from that just described is used. This arrangement, referring now also to FIGS. 4 and 5, includes a flexible fluid conduit '92 connected at one end to fitting 80 and hence conduits 78 and 72, looped between intermediate slide 24 and mast 22 and connected at the other end to a fitting 94 which is mounted on a bracket 96 connected to one of channels 34 of mast 22. Also connected to fitting 94 and hence conduit 92 is a short length of rigid conduit 98 which in turn is connected to another flexible conduit 100 that is fastened to the adjacent channel 34 by a plurality of clips 102 and run down to the lower right-hand corner of mast 22 where it is run over to truck 10 and connected to a control valve, not shown, mounted on the body of truck 10. Also, a flexible conduit 104 is connected at one end thereof to fitting 90 and hence conduits 88 and 84, looped between intermediate slide 24 and mast 22 and connected at the other end thereof to a fitting 106 mounted on bracket 96. A short length of rigid fluid conduit 108 is connected at one end thereof to fitting 106 and hence to conduit 104 and at the other end thereof to a flexible conduit 110 is fastened to mast 22 by clips 102 and in turn is connected to the aforementioned control valve, the same as conduit 100. By proper manipulation of the control valve the operator may direct pressurized fluid to either conduit 100 or 110 while the other conduit is then connected to the fluid reservoir, or supply pressurized fluid to neither of the conduits.

As can be seen from viewing FIGS. 4 and especially, the loops formed by flexible conduits 92 and 104 are oriented oppositely to each other. This is accomplished by reeving conduit 92 over a dual sheave assembly 112 and reeving conduit 104 under a dual sheave assembly 114. Again, a dual sheave assembly suitable for use here is disclosed and claimed in the aforementioned US. patent application. Sheave assembly 112 is connected for rotation to a bracket 116, and similarly sheave assembly 114 is connected to a bracket 118. Brackets 116 and 118 are connected to a bar 120 which is made up of a pair of parallel plates 122 that are connected by two pairs of spacers 124 and 126. v,

Bar 120, together with sheave assemblies 112 and 114, is restrained from movement away from mast 22 and intermediate slide 24 and guided for movement longitudinally thereof by means of a pair of U-shaped guides 128 connected to bracket 82 and hence intermediate slide 24, guides 128 engaging the edges of one of plates 122 of bar 120, as shown, and a pair of U-shaped guides 130 which engage the edges of the other plate 122, as shown, and which are connected to bracket 96 and hence mast 22. It will be noted that bracket 82 and guides 128 are disposed on one side of bar 120 and that bracket 96 and guides 130 are disposed on the other side of bar 120, each pair of guides engaging different ones of plates 122 so that during extension of intermediate slide 24 there is no interference between the brackets and guides as they pass each other. Thus, when intermediate slide 24 is raised, the ends of conduits 92 and 104 which are connected to fittings and move upwardly with intermediate slide 24 since the fittings are connected to bracket 82 which in turn is connected to intermediate slide 24. Upward movement of conduits 92 and 104 also causes bar 120, together with sheave assemblies 112 and 114, to shift upwardly.

Referring especially to FIGS. 4 and 5, there is connected to bracket '82 a sheave or wheel 132 which is mounted for rotation on a shaft 136. Located adjacent sheave 132 and extending rearwardly from bracket 82 is a plate 138 to which a pair of open ended tubes 140 and 142 are connected. Extending through plate 138 and communicating with the interior of tubes 140 and 142 are a pair of openings 144 and 146. The function of this structure will be explained shortly.

Returning now to valve 54 it will be recalled that a pair of solenoids 56 and 58 were connected thereto for actuating the valve spool to connect ports 60' and 62 with various pairs of motor ports so that more than one fluid motor can be operated from a single pair of supply and return conduits. Obviously, solenoids 56 and 58 must be connected by electrical conductors to a control switch which in turn opens and closes a circuit between each solenoid and a source of electrical power, such as a battery or a generator.

Connected to solenoid 56 is an electrical conductor 148 which is reeved over sheave assembly 74, fastened to intermediate slide 24 by means of a clip 150, run through tube 140 and opening 144 in plate 138, around sheave 132, under sheave assembly 114, fastened to conduit 104 adjacent fitting 106 by a clip 152, run down alongside conduits and to a lower corner of mast 22 and then to an on-off switch (not shown) on truck 10. Also, conductor 148 passes through a helical compression spring 152 disposed in tube between plate 138 and a stop 154 connected to conductor 148. Stop 154 is disposed so that spring 152 is under compression at all times, whereby conductor 148 is maintained under tension and taut at all times.

Connected to solenoid 58 is an electrical conductor 156 which is reeved over sheave assembly 85, fastened to intermediate slide 24 by means of clip 150, passed through tube 142 and opening 146, trained around sheave 132, reeved over sheave assembly 112, fastened to fluid conduit 92 adjacent fitting 94 by a clip 158 and then run down along one side of mast 22 to a lower corner thereof and to an on-olf switch, not shown, mounted on truck 10. It will be noted that conductor 156 passes through a helical spring 160 which is disposed in tube 142 between plate 138 and a stop 162 which is fastened to conductor 156. Stop 162 is located so that spring 160 is under compression at all times, whereby conductor 156 is maintained under tension and taut at all times.

The various fluid conduits, including conduits 92 and 104, are made of an elastic material. Consequently, when pressurized fluid is supplied to one of the conduits the conduit tends to swell and as a result of this the conduit also shortens by approximately four percent. In other words, as the cross section of the conduit varies the length of the conduit varies inversely. Thus, FIG. 4 shows the condition of conduits 92 and 104 and the apparatus associated therewith when pressurized fluid is supplied to neither of these conduits. If pressurized fluid, for example, is supplied to conduit 104 causing it to shorten, then bar 120, together with sheave assemblies 112 and 114, shifts upwardly causing conduit 92 to stretch slightly. Since electrical conductor 156 is substantially nonstretchable, upward movement of sheave assembly 112 pulls on conductor 156 in order to gain additional length to compensate for upward movement of sheave assembly 112, thereby compressing spring 160 further. At the same time the length of conductor 148 necessary to extend between plate 138 and clip 150 decreases so that spring 152 expands, thereby compensating for the additional length of conductor 148 which is available. As a result both conductors 148 and 156 are maintained taut and excessive tension is prevented from being exerted on the conductor which must in eflect lengthen between plate 138 and the clip to which it is attached to'the adjacent conduit.

Although only a single preferred embodiment of my invention has been disclosed in the foregoing detailed description, it will be understood that the description is intended to the illustrative only, and that my invention is subject to various modifications and changes by persons skilled in the art which nonetheless would fall within the scope and spirit of my invention.

I claim:

1. The combination comprising a first member, a second member movable relative to the said first member, first and second elastic fluid conduits looped between and connected to the said members, first and second flexible electrical conductors looped between and connected to the said members, means engaging the said conduits and conductors for orienting the loops of the said first conduit and first conductor generally oppositely to the loops of the said second conduit and second conductor, guide means connected to one of the said members intermediate said conduits and engaging the said conductors for guiding the conductor immediate adjacent a said conduit in an opposite direction, and resilient means connected between each of the said conductors and the said one member for maintaining tension on each of the said conductors.

2. The combination as set forth in claim 1 wherein the said orienting means includes a bar, first and second sheave assemblies mounted for rotation on the said bar and means connected to at least one of the said members for guiding and restraining the said bar, the said first sheave assembly engaging the loops of the said first conduit and first conductor and the said second sheave assembly engaging the loops of the said second conduit and second conductor.

3. The combination as set forth in claim 1 wherein the said guide means includes a pair of sheaves.

4. The combination as set forth in claim 3 wherein the said sheaves are mounted for independent rotation on the said one member and are disposed coaxially relative to each other and the said electrical conductors are trained in opposite directions around different ones of the said sheaves.

5. The combination as set forth in claim 1 wherein the said tension maintaining means includes a plate through which the said conductors pass, a first stop connected to the said first conductor, a compression spring disposed between and abutting the said plate and first stop, a second stop connected to the said second conductor and a compression spring disposed between and abutting the said plate and second stop.

6. The combination as set forth in claim 3 wherein the resilient tension maintaining means includes a plate through which the said conductors pass, a first stop connected to the said first conductor, a compression spring disposed between and abutting the said plate and first stop, a second stop connected to the said second conductor and a compression spring disposed between and abutting the said plate and second stop.

7. The combination as set forth in claim 6 wherein the said sheaves are mounted for independent rotation on the said one member and are disposed coaxially relative to each other and the said electrical conductors are trained in opposite directions around different ones of the said sheaves.

8. The combination as set forth in claim 2 wherein the said guide means includes a pair of wheels disposed coaxially relative to each other and mounted for independent rotation on said one member, the said first conductor running in one direction around one of the said wheels and the said second conductor running in the opposite direction around the other of said wheels.

9. The combination as set forth in claim 8 wherein the resilient tension maintaining means includes a plate through which the said conductors pass, a first stop connected to the said first conductor, a compression spring disposed between and abutting the said plate and first stop, a second stop connected to the said second conductor and a compression spring disposed between and abutting the said plate and second stop.

10. The combination comprising a first member, a second member movable relative to the said first member, a first flexible fluid conduit having a variable cross section and a length which varies inversely relative to the cross section thereof, the said first conduit being looped between and connected to the said members, a second flexible fluid conduit having a variable cross section and a length which varies inversely relative to the cross section, the said second conduit being looped between and connected to the said members, the said conduits shortening when pressurized fluid is supplied to them, a first flexible electrical conductor having a substantially fixed length, the said first conductor being looped between and connected to the said members, a second electrical conductor having a substantially fixed length, the said second conductor being looped between and connected to the said members, means engaging the said conduits and conductors for orienting the loops of the said first conduit and the said first conductor generally oppositely t0 the loops of the said second conduit and the said second conductor, and means for preventing excessive tension being applied to one of the said conductor loops when pressurized fluid is supplied to the conduit loop which is oriented generally oppositely to the said one conductor loop, the said excessive tension preventing means including wheel means connected to one of the said members, the said conductors being reeved in opposite direc tions around the said wheel means and in opposite direction relative to an adjacent conduit, resilient means connected between the said first conductor and the said one member for maintaining tension on the said first conductor and resilient means connected between the said second conductor and the said one member for maintaining tension on the said second conductor.

References Cited UNITED STATES PATENTS 1,351,867 9/1920 Oakes 242-47.5 2,800,236 7/ 1957 Schenkelbeiger 2145l4 2,979,162 4/1961 Quayle l879 3,305,220 2/1967 Nevulis 2l255 X FOREIGN PATENTS 593,563 5/1959 Italy.

GERALD M. FORLENZA, Primary Examiner R. B. JOHNSON, Assistant Examiner US. Cl. X.R. 214-650 

